Using solar (and attached direct) cylinders as heat stores

[GregKaye]

Thermal stores are still available & still have there place but as said before the amount of hot water (heat energy) you would need to store to provide for domestic heating & HW often means they are impractical.

thanks.
its appreciated to get advice from an actual pro 🙂

 

[GregKaye]

Looks similar to a wet (heating only) system I installed years ago at an outdoor centre. Place was off-grid and previously relied on a generator which had been replaced by a wind turbine and solar PV feeding battery storage & inverters with the genny as backup. Existing turbine controls dumped excess energy into a large resistor heating up the locality once the batteries were charged. We fitted a 1000L buffer tank with 4kW immersion heaters (8x500W) switched by the existing controls so instead of wasting energy it was used to preheat the tank. Heating was weather compensated with 3-way valve. According to the site manager the boiler hardly ran at times in spring and autumn.
Water might not be the best material for thermal storage but it's the easiest to install without getting expensive.

Thanks, its also easy to get the heat out of water which, at times when people might not want to use much energy, has its own value.

 

[GregKaye]

Remember water is actually a rubbish medium for heat transfer as it's shc is so high. We'd be better off using a different medium but it'd be more expensive and less 'simple' to service.

That's new to me. I thought that a high specific heat capacity was a good thing. I thought it meant that more heat could be contained.

 

[Welder]

That's new to me. I thought that a high specific heat capacity was a good thing. I thought it meant that more heat could be contained.

It's that double edged sword Greg. Reasonable retention but hard as hell to heat.

 

[Brambles]

We design and instal, one off renewable energy solutions, generally for larger properties or small commercial premises. In essence your scheme is viable, but would require a fairly complex control system to optimise the performance - the inclusion of the intermittent heat pump (gym powered) significantly adds to the complexity of the system. Heat pumps ideally need to be operational 24/7

In general, if you can design around standard components a neater more economic solution would be achieved.

Three or four coil tanks are only viable with tank capacities greater than 500 litres.

If you are looking for the system to be granted RHI status, then it would need to be designed strictly in accordance to the RHI scheme rules

Hope this helps

 

[Chrisjones.7976]

To store enough water for heating isn't on. You would need a massive amount of storage, just think how much water is contained in a central heating system & multiply it by the number of changes you need to keep the house warm. Yes you can get 3 coil cylinders, I have one, the intermediate coil above the solar one is heated by a wood stove, the boiler heats the top one. I also have an immersion heater which is fed by PV solar panels to stop the surplus electricity going back into the grid.

Regards

Chris

 

[Stigster]

To store enough water for heating isn't on. You would need a massive amount of storage, just think how much water is contained in a central heating system & multiply it by the number of changes you need to keep the house warm.
Chris

This was exactly the problem with our local brand Ecostor heatstores. You put the heating on in the morning and your thermal store was full of luke warm water in about an hour, no good for bathing in conjunction with that. Ecostor were usually 300 litres volume I believe and even that would only work with very careful timed use of the system or in a bedsit with 2 rads and one shower, usually electric!